omap: iommu: fix wrong condition check for SUPERSECTION

A bit (2 << 0) is set both on SECTION and SUPERSECTION. To identify
SUPERSECTION correctly, other bits should be compared too.

Reported-by: "Srinivas Pulukuru" <srinivas.pulukuru@ti.com>
Signed-off-by: Hiroshi DOYU <Hiroshi.DOYU@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>